Dallas defensive end Anthony Spencer stops in a locker room filled with rookies, the eight-year veteran's beard dripping with sweat after the latest workout in his attempt to come back from microfracture surgery on his left knee.

Spencer feels like a first-year guy again, except that he isn't. He is a 30-year-old player without a timetable for a return, not even sure if he will play again.

"The injury, it's really uncommon," said Spencer, who missed all but one game and had two knee surgeries in two months in 2013. "You rarely see guys coming back from it. I'm just on my body schedule. Wherever my body is, that's where I am."

The Cowboys decided to bring back Spencer on a third straight one-year deal at a fraction of what he cost with the franchise tag in consecutive seasons. If he makes it all the way back and hits all the incentives, he will earn $3.5 million -- a third of his salary a year ago.

Dallas isn't waiting for him, either. The Cowboys signed three other free agents on the defensive line and drafted three more a week ago.

Their answer to the release of franchise sacks leader DeMarcus Ware was surrendering a third-round draft pick to move up in the second round and get Boise State's DeMarcus Lawrence, who went through his first rookie practice Saturday after missing the first day to attend the birth of his son.

If Spencer plays two years after getting a career-high 11 sacks and finishing just half a sack behind Ware, it will be a bonus, not a necessity.

"I don't know that you can count on any injured player to come back," coach Jason Garrett said. "You've got to make sure that you have safety nets and reinforcements. We certainly did that across our defensive line."

Spencer missed the offseason and training camp last year because of knee trouble before working his way back and playing in Week 2 at Kansas City. But the pain wouldn't go away.

He was on crutches for about four months after microfracture surgery, which repairs cartilage that cushions bones in the knee and doesn't offer any guarantees that pro athletes can regain the form they had before the procedure.

Now he is finally getting in cardiovascular work and lifting weights, and will soon do some light work on the field. But don't ask if he'll get back for any of training camp. Or a preseason game. Or any other game.

"I've gotten to where I am by listening to my body and rehabbing and doing things at the pace of my body," Spencer said. "That's one of the biggest things with this surgery I've read is just being patient. I'm just not pushing it anywhere past that."

If he does get back, Spencer will be the only familiar face on a revamped front four. Ware signed with Denver a day after the Cowboys released him, and 2013 sacks leader Jason Hatcher went to Washington. Jay Ratliff didn't play a down for the Cowboys last year before his midseason release.

"That's probably the biggest change of it all," Spencer said. "I've been here six, seven years now and seen so many guys come and go. This is the way things work."

Garrett isn't counting on Spencer. But he's not counting him out, either.

"There have been players who have come back from an injury like Spence's," the coach said. "And when you have Spence's character, his makeup, the kind of person he is, you certainly want to give him every chance."